Abstract:

Process for preparing cyclometallated transition metal-carbene complexes
comprising at least one carbene ligand, which comprises reacting a ligand
precursor with a base, an auxiliary reagent and a metal complex
comprising at least one metal M1 (route A) or reacting the ligand
precursor with a basic auxiliary reagent and a metal complex comprising
at least one metal M1 (route B). The present invention further
relates to the use of an auxiliary reagent selected from among salts
comprising at least one metal selected from the group consisting of Ag,
Hg, Sb, Mg, B and Al together with a base in a process for preparing
cyclometallated metal complexes.

Claims:

1-13. (canceled)

14. A process for preparing cyclometallated carbene complexes of the
general formula (1) comprising at least one carbene ligand ##STR00043##
where the symbols have the following meanings:M1 is a metal atom
selected from the group consisting of Ir, Co, Rh, Ni, Pd, Pt, Fe, Ru, Os,
Cr, Mo, W, Mn, Tc, Re, Cu and Au in any oxidation state possible for the
respective metal atom;carbene is a carbene ligand of the general formula
(II) ##STR00044## L is a monoanionic or dianionic ligand which may be
monodentate or bidentate;K is an uncharged monodentate or bidentate
ligand;n is the number of carbene ligands, with n being at least 1, and
the carbene ligands in the complex of the formula I being able to be
identical or different in the case of n>1;m is the number of ligands
L, with m being able to be 0 or ≧1 and the ligands L being able to
be identical or different in the case of m>1;o is the number of
ligands K, with o being able to be 0 or ≧1 and the ligands K being
able to be identical or different in the case of o>1;where the sum
n+m+o is dependent on the oxidation state and coordination number of the
metal atom used and on the denticity of the ligands carbene, L and K and
also on the charge on the ligands carbene and L, with the proviso that n
is at least 1;where the symbols in the carbene ligand of the general
formula II have the following meanings:Do1 is a donor atom selected
from the group consisting of C, P, N, O, S and Si;Do2 is a donor
atom selected from the group consisting of C, N, P, O and S;r is 2 when
Do1 is C or Si, is 1 when Do1 is N or P and is 0 when Do1
is O or S;s is 2 when Do2 is C, is 1 when Do2 is N or P and is
0 when Do2 is O or S;X is a spacer selected from the group
consisting of silylene, alkylene, arylene, heteroarylene, alkynylene,
alkenylene, NR13, PR14, BR15, O, S, SO, SO2, CO,
CO--O, O--CO and (CR16R17)w, where one or more nonadjacent
(CR16R17) groups can be replaced by NR13, PR14,
BR15, O, S, SO, SO2, CO, CO--O, O--CO;w is from 2 to
10;R13, R14, R15, R16, R17 are each H, alkyl,
aryl, heteroaryl, alkenyl, alkynyl;p is 0 or 1;q is 0 or 1;Y1,
Y2 are each, independently of one another, hydrogen or a
carbon-comprising group selected from the group consisting of alkyl,
aryl, heteroaryl, alkynyl and alkenyl groups;orY1 and Y2
together form a bridge between the donor atom Do1 and the nitrogen
atom N which has at least two atoms, of which at least one is a carbon
atom,Y3 is hydrogen, an alkyl, aryl, heteroaryl, alkynyl or alkenyl
radical;or ##STR00045## where Do2', q', s', R3', R1',
R2', X' and p' independently have the same meanings as Do2, q,
s, R3, R1, R2, X and p;with Y3 and Y2 also being
able to be joined to one another via a bridge which can have the
following meanings:alkylene, arylene, heteroarylene, alkynylene,
alkenylene, NR25, PR26, BR27, O, S, SO, SO2,
SiR32R33, CO, CO-0, O--CO and (CR28R29)y, where
one or more nonadjacent (CR28R29) groups may be replaced by
NR25, PR26, BR27, O, S, SO, SO2, SiR32R33,
CO, CO--O, O--CO, wherey is from 2 to 10;andR25, R26, R27,
R28, R29, R32, R33 are each H, alkyl, aryl,
heteroaryl, alkenyl, alkynyl;R1, R2 are each, independently of
one another, hydrogen or an alkyl, aryl, heteroaryl, alkynyl or alkenyl
radical,orR1 and R2 together form a bridge having a total of
from three to five atoms, of which one or two atoms can be heteroatoms,
and the remaining atoms are carbon atoms, so that the group ##STR00046##
forms a five- to seven-membered ring which may optionally have, in
addition to the existing double bond, one further double bond or in the
case of a six- or seven-membered ring two further double bonds and may
optionally be substituted by alkyl or aryl groups and/or groups having a
donor or acceptor action and may optionally comprise at least one
heteroatom;with Y1 and R1 also being able to be joined to one
another via a bridge which can have the following meanings:alkylene,
arylene, heteroarylene, alkynylene, alkenylene, NR18, PR19,
BR20, O, S, SO, SO2, SiR30R31, CO, CO--O, O--CO and
(CR21R22)x, where one or more nonadjacent
(CR21R22) groups may be replaced by NR18, PR19,
BR20, S, SO, SO2, SiR30R31, CO, CO--O, O--CO, wherex
is from 2 to 10;andR18, R19, R20, R21, R22,
R30, R31 are each H, alkyl, aryl, heteroaryl, alkenyl,
alkynyl;R3 is hydrogen or an alkyl, aryl, heteroaryl, alkynyl or
alkenyl radical;which comprises reaction of a ligand precursor of the
general formula (III) ##STR00047## whereQ.sup.- is a monoanionic
counterion,andG is H when Do2=C andis H or a free electron pair when
Do2=N, S, O or P;andthe further symbols in the ligand precursor of
the formula III have the meanings given in respect of the ligand of the
formula II,whereinthe reaction comprises the use of a baxic auxiliary
reagent comprising at least one metal selected from the group consisting
of Ag (route B) and the ligand precursor of the general formula III is(B)
reacted with the basic auxiliary reagent to give a protected carbene and
the protected carbene is subsequently reacted without further work-up
and/or purification with a metal complex comprising at least one metal
M1 (route B);to give a cyclometallated carbene complex of the
formula I.

15. The process according to claim 14, wherein the group ##STR00048## is
selected from the group consisting of ##STR00049## where the symbols have
the following meanings:R4, R5, R6,R7, R8,
R9, R11 and R11' are each hydrogen, alkyl, aryl,
heteroaryl, alkynyl or alkenyl or a substituent having a donor or
acceptor action;R10 is alkyl, aryl, heteroaryl, alkynyl or alkenyl
or 2 radicals R10 together form a fused-on ring which may optionally
comprise at least one heteroatom or R10 is a radical having a donor
or acceptor action;with R4 or R5 in the group a, R8 in the
group b, one of the radicals R10 in the group c and R11 in the
group d also being able to be linked to R1 via a bridge which can
have the following meanings:alkylene, arylene, heteroarylene, alkynylene,
alkenylene, NR18, PR19, BR20, S, SO, SO2,
SiR30R31, CO, CO--O, O--CO and (CR21R22)x, where
one or more nonadjacent (CR21R22) groups can be replaced by
NR18, PR19, BR20, S, SO, SO2, SiR30R31, CO,
CO--O, O--CO, wherex is from 2 to 10;andR18, R19, R20,
R21, R22, R30, R31 are each H, alkyl, aryl,
heteroaryl, alkenyl, alkynyl;v is from 0 to 4, where, when v is 0, the
four carbon atoms of the aryl radical in formula c which may optionally
be substituted by R10 bear hydrogen atoms;Y3 is hydrogen, an
alkyl, aryl, heteroaryl, alkynyl or alkenyl radical; or ##STR00050##
where Do2', q', s', R3', R1', R2', X' and p'
independently have the same meanings as Do2, q, s, R3, R1,
R2, X and p.

16. The process according to claim 14, wherein the group ##STR00051## is
the structure ##STR00052## where the symbols have the following
meanings:Z is CH or N, where from 0 to 3 of the symbols Z can be
N;R12 is an alkyl, aryl, heteroaryl, alkynyl, alkenyl radical, or 2
radicals R12 together form a fused-on ring which may optionally
comprise at least one heteroatom, or R12 is a radical having a donor
or acceptor action;with the group of the structure ##STR00053## also
being able to be linked via the aromatic basic skeleton or via one of the
radicals R12 to Y1 via a bridge which can have the following
meanings:alkylene, arylene, heteroarylene, alkynylene, alkenylene,
NR18, PR19, BR20, O, S, SO, SO2, SiR30R31,
CO, CO--O, O--CO and (CR21R22)x, where one or more
nonadjacent (CR21R22) groups may be replaced by NR18,
PR19, BR20, S, SO, SO2, SiR30R31, CO, CO--O,
O--CO, wherex is from 2 to 10;andR18, R19, R20, R21,
R22, R30, R31 are each H, alkyl, aryl, heteroaryl,
alkenyl, alkynyl;t is from 0 to 4, where, when t is >1, the radicals
R12 can be identical or different.

17. The process according to any of claims 14, wherein the at least one
carbene ligand is selected from the group consisting of ##STR00054##
##STR00055## where the symbols have the following meanings:Z, Z', Z'' are
identical or different and are each CH or N;R12, R12' are
identical or different and are each an alkyl, aryl, heteroaryl, alkynyl
or alkenyl radical, or 2 radicals R12 or R12' together form a
fused-on ring which may optionally comprise at least one heteroatom, or
R12 or R12' is a radical having a donor or acceptor action;t
and t' are identical or different and are each from 0 to 4, where, when t
or t' is >1, the radicals R12 or R12' can be identical or
different;R4, R5, R6 R7, R8, R9 and
R11 are each hydrogen, alkyl, aryl, heteroaryl, alkynyl or alkenyl
or a radical having a donor or acceptor action;R10 is alkyl, aryl,
heteroaryl, alkynyl or alkenyl, or 2 radicals R10 together form a
fused-on ring which may optionally comprise at least one heteroatom, or
R10 is a radical having a donor or acceptor action;with the group of
the structure ##STR00056## also being able to be joined via the aromatic
basic skeleton or via one of the radicals R12 to R4 or R5
or the carbon atom to which R4 and R5 are bound in the groups a
and f, R8 or the carbon atom to which R8 is bound in the groups
b and g, one of the radicals R10 or one of the carbon atoms to which
R10 is bound in the groups c and h and R11 or the carbon atom
to which R11 is bound in the groups d and i via a bridge which can
have the following meanings:alkylene, arylene, heteroarylene, alkynylene,
alkenylene, NR18, PR19, BR20, S, SO, SO2,
SiR30R31, CO, CO--O, O--CO and (CR21R22)x, where
one or more nonadjacent (CR21R22) groups may be replaced by
NR18, PR19, BR20, S, SO, SO2, SiR30R31, CO,
CO--O, O--CO, wherex is from 2 to 10;andR18R19, R20,
R21, R22, R30, R31 are each H, alkyl, aryl,
heteroaryl, alkenyl, alkynyl;where in the cases in which the group of the
structure ##STR00057## is linked via a bridge to the carbon atom to which
R4 and R5 are bound (groups a and f), the carbon atom to which
R8 is bound (groups b and g), one of the carbon atoms to which
R10 is bound (groups c and h) or the carbon atom to which R1 is
bound (groups d and i), and the respective radical R4 or R5,
R8, one of the radicals R10 and R11 is replaced by a bond
to the bridge;v is from 0 to 4, where, when v is 0, the four carbon atoms
of the aryl radical in formulae c and h which may optionally be
substituted by R10 bear hydrogen atoms;Y3 is hydrogen, an
alkyl, aryl, heteroaryl, alkynyl or alkenyl radical.

18. The process according to any of claim 14, wherein(B) the ratio of
metal complex comprising at least one metal M1, ligand precursor of
the formula III and basic auxiliary reagent is 1:1-10:0.5-5 per metal
atom M1 and number of carbene ligands n (route B).

19. The process according to any of claims 14, wherein the process is
carried out in a solvent.

20. The process according to claim 14, wherein Ir is used as metal
M.sup.1.

21. The process according to any of claim 14, wherein Ag2O,
Ag2CO3, AgOAc and/or Ag2S, is used as a basic auxiliary
reagent in route B.

Description:

[0001]The present invention relates to a process for preparing
cyclometallated transition metal-carbene complexes comprising at least
one carbene ligand, which comprises reacting a ligand precursor with a
base, an auxiliary reagent and a metal complex comprising at least one
metal M1 (route A) or reacting the ligand precursor with a basic
auxiliary reagent and a metal complex comprising at least one metal
M1 (route B). The pre-sent invention further relates to the use of
an auxiliary reagent selected from among salts comprising at least one
metal selected from the group consisting of Ag, Hg, Sb, Mg, B and Al
together with a base in a process for preparing cyclometallated metal
complexes.

[0002]Organic light-emitting diodes (OLEDs) exploit the ability of
materials to emit light when they are excited by an electric current.
OLEDs are of particular interest as alternatives to cathode ray tubes and
liquid crystal displays for producing flat VDUs. Owing to their very
compact construction and intrinsically lower power consumption, devices
comprising OLEDs are particularly suitable for mobile applications, for
example for use in mobile telephones, laptops, etc.

[0003]Numerous materials which emit light on excitation by an electric
current have been proposed.

[0004]WO2005/019373 discloses the use of transition metal complexes
comprising at least one carbene ligand in organic light-emitting diodes
(OLEDs). These are prepared by deprotonation of the corresponding ligand
precursors and subsequent reaction with suitable metal complexes
comprising the desired metal without addition of further auxiliary
reagents. Here, the yields of the transition metal complexes obtained are
sometimes in need of improvement.

[0005]The prior art discloses processes in which transition metal-carbene
complexes are pre-pared in the presence of silver-comprising auxiliary
reagents. Known processes involve, in particular, the use of Ag2O
for preparing silver-carbene complexes and sub-sequent carbene transfer
to other metals and also the use of silver salts such as AgBF4,
AgCO2CF3, AgPF6, AgOTf for halide abstraction and for
anion exchange in metal-carbene complexes.

[0006]Mark E. Thompson et al., Inorganic Chemistry, 2005, 44, 7992-8003,
describe iridium complexes with cyclometallated N-heterocyclic carbene
ligands (NHC). The preparation of iridium complexes bearing three
cyclometallated carbene ligands (C C:) is carried out by reacting the
corresponding imidazolium (pmiH.sup.+) or benzimidazolium (pmbH.sup.+)
iodide salts with silver(I) oxide (Ag2O) and iridium(III) chloride
hydrate under reflux in 2-ethoxyethanol in one step, giving a mixture of
the desired fac- and mer-Ir(C C:)3 complexex in low yields
(according to the description <10%) together with a product of the
formula [(C C:)2IrCl]2. The product of the formula [(C
C:)2IrCl]2 can in turn be reacted with the corresponding
imidazolium or benzimidazolium iodide salts and Ag2O in
1,2-dichloroethane to form fac- and mer-Ir(C C:)3 complexes in order
to increase the yield.

[0007]WO2005/113704 relates to luminescent compounds bearing carbene
ligands. The compounds can be, inter alia, iridium-(benz)imidazolylidene
carbene complexes. In the examples, these are prepared in one step by
reacting the corresponding (benz)imidazolium iodide salts with Ag2O
and iridium(III) chloride hydrate. The yields of the desired iridium
complexes are low.

[0008]Steven P. Nolan et al. J. Am. Chem. Soc. 2004, 126, 5054-5055,
describe cyclometallated N-heterocyclic carbene complexes (NHC) of
rhodium. According to the description, the doubly cyclometallated complex
RhCl(N,N-di(tert-butyl)imidazol-2-ylidene))2 is prepared by reacting
[Rh(COE)2Cl]2 with N,N-di(tert-butyl)imidazol-2-ylidene) in
benzene. This can, in a further step, be converted into a 14 electron
Rh(III) complex by reaction with AgPF6 in CH2Cl2. The
silver salt is used by Steven P. Nolan et al. for the abstraction of
Cl.sup.-. CH activation is present before the addition of the silver
salt.

[0009]Alfred F. Noels et al., Can. J. Chem. 79: 529-535 (2001) describe,
inter alia, the preparation of the cyclometallated Ru complex
RuCl(p-cymene)(triazolinylidene) by stoichiometric reaction of
triazolinylidene carbene
(1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene) with the dimeric
Ru complex [RuCl2(p-cymene)]2 with addition of an excess of a
base (EtN-i-Pr2). The corresponding cationic complex is obtained
from this complex by abstraction of Cl.sup.- by means of AgBF4 in
acetonitrile. Alfred F. Noels et al. thus use the silver salt, as do
Steven P. Nolan et al., for the abstraction of Cl.sup.-. CH activation is
present before the addition of the silver salt.

[0010]It is an object of the present invention to provide a process for
preparing cyclometallated carbene complexes, in particular
Ir(III)-carbene complexes, in which the complexes are obtained in good
yields in a simple reaction procedure.

[0011]This object is achieved by a process for preparing cyclometallated
carbene complexes of the general formula (I) comprising at least one
carbene ligand

##STR00001##

where the symbols have the following meanings: [0012]M1 is a metal
atom selected from the group consisting of Ir, Co, Rh, Ni, Pd, Pt, Fe,
Ru, Os, Cr, Mo, W, Mn, Tc, Re, Cu and Au, preferably Ir, Os, Ru, Rh, Pd,
Co and Pt, particularly preferably Ir, Pt, Rh and Os, very particularly
preferably Ir, in any oxidation state possible for the respective metal
atom, more preferably Ir(I) and Ir(III) and in particular Ir(III);
[0013]carbene is a carbene ligand of the general formula (II)

[0013] ##STR00002## [0014]L is a monoanionic or dianionic ligand which
may be monodentate or bidentate; [0015]K is an uncharged monodentate or
bidentate ligand; [0016]n is the number of carbene ligands, with n being
at least 1, preferably at least 2, and the carbene ligands in the complex
of the formula I being able to be identical or different in the case of
n>1; [0017]m is the number of ligands L, with m being able to be 0 or
≧1 and the ligands L being able to be identical or different in
the case of m>1; [0018]o is the number of ligands K, with o being able
to be 0 or ≧1 and the ligands K being able to be identical or
different in the case of o>1; [0019]where the sum n+m+o is dependent
on the oxidation state and coordination number of the metal atom used and
on the denticity of the ligands carbene, L and K and also on the charge
on the ligands carbene and L, with the proviso that n is at least 1;
[0020]where the symbols in the carbene ligand of the general formula II
have the following meanings: [0021]Do1 is a donor atom selected from
the group consisting of C, P, N, O, S and Si, preferably P, N, O and S,
particularly preferably N; [0022]Do2 is a donor atom selected from
the group consisting of C, N, P, O and S; [0023]r is 2 when Do1 is C
or Si, is 1 when Do1 is N or P and is 0 when Do1 is O or S;
[0024]s is 2 when Do2 is C, is 1 when Do2 is N or P and is 0
when Do2 is O or S; [0025]X is a spacer selected from the group
consisting of silylene, alkylene, arylene, heteroarylene, alkynylene,
alkenylene, NR13, PR14, BR15, O, S, SO, SO2, CO,
CO--O, O--CO and (CR16R17)w, where one or more nonadjacent
(CR16R17) groups can be replaced by NR13, PR14,
BR15, O, S, SO, SO2, CO, CO--O, O--CO, preferably alkylene,
arylene, alkenylene, silylene, SO or SO2, particularly preferably
C1-C3-alkylene, C6-1,2-arylene or C2-alkenylene,
where at least one of the carbon atoms of the groups mentioned as spacer
may optionally be substituted, for example, by methyl, ethyl, n-propyl or
i-propyl groups or by groups having a donor or acceptor action selected
from among halogen radicals, preferably F, Cl, Br, particularly
preferably F, alkoxy radicals, aryloxy radicals, carbonyl groups, ester
groups, amino groups, amide radicals, CHF2, CH2F, CF3, CN,
thio groups and SCN, very particularly preferably methylene, ethenylene
or 1,2-phenylene; [0026]w is from 2 to 10; [0027]R13, R14,
R15, R16, R17 are each H, alkyl, aryl, heteroaryl,
alkenyl, alkynyl; [0028]p is 0 or 1, preferably 0; [0029]q is 0 or 1,
preferably 0; [0030]Y1, Y2 are each, independently of one
another, hydrogen or a carbon-comprising group selected from the group
consisting of alkyl, aryl, heteroaryl, alkynyl and alkenyl groups;
[0031]or [0032]Y1 and Y2 together form a bridge between the
donor atom Do1 and the nitrogen atom N which has at least two atoms,
preferably two or three atoms, particularly preferably two atoms, of
which at least one is a carbon atom and the further atoms are preferably
nitrogen or carbon atoms, with the bridge being able to be saturated or
unsaturated, preferably unsaturated, and the at least two atoms of the
bridge being able to be substituted or unsubstituted; [0033]Y3 is
hydrogen, an alkyl, aryl, heteroaryl, alkynyl or alkenyl radical,
preferably an alkyl, heteroaryl or aryl radical, particularly preferably
an alkyl radical; [0034]or

[0034] ##STR00003## [0035]where Do2', q', s', R3',
R1', R2', X' and p' independently have the same meanings as
Do2, q, s, R3, R1, R2, X and p; [0036]with Y3
and Y2 also being able to be joined to one another via a bridge
which can have the following meanings: [0037]alkylene, arylene,
heteroarylene, alkynylene, alkenylene, NR25, PR26, BR27,
O, S, SO, SO2, SiR32R33, CO, CO--O, O--CO and
(CR28R29)y, where one or more nonadjacent
(CR28R29) groups may be replaced by NR25, PR26,
BR27, O, S, SO, SO2, SiR32R33, CO, CO--O, O--CO,
where [0038]y is from 2 to 10; [0039]and [0040]R25, R26,
R27, R28, R29, R32, R33[0041]are each H,
alkyl, aryl, heteroaryl, alkenyl, alkynyl; [0042]R1, R2 are
each, independently of one another, hydrogen or an alkyl, aryl,
heteroaryl, alkynyl or alkenyl radical, preferably hydrogen, an alkyl
radical, a heteroaryl radical or an aryl radical, [0043]or [0044]R1
and R2 together form a bridge having a total of from three to five
atoms, preferably four atoms, of which one or two atoms can be
heteroatoms, preferably N, and the remaining atoms are carbon atoms, so
that the group

[0044] ##STR00004## [0045]forms a five- to seven-membered, preferably
six-membered, ring which may optionally have, in addition to the existing
double bond, one further double bond or in the case of a six- or
seven-membered ring two further double bonds and may optionally be
substituted by alkyl or aryl groups and/or groups having a donor or
acceptor action and may optionally comprise at least one heteroatom,
preferably N, with preference being given to a six-membered aromatic ring
which is unsubstituted or substituted by alkyl or aryl groups, or the
preferred six-membered aromatic ring is fused with further rings which
may optionally comprise at least one heteroatom, preferably N, preferably
six-membered aromatic rings; [0046]with Y1 and R1 also being
able to be joined to one another via a bridge which can have the
following meanings: [0047]alkylene, arylene, heteroarylene, alkynylene,
alkenylene, NR18, PR19, BR20, O, S, SO, SO2,
SiR30R31, CO, CO--O, O--CO and (CR21R22)x, where
one or more nonadjacent (CR21R22) groups may be replaced by
NR18, PR19, BR20, O, S, SO, SO2, SiR30R31,
CO, CO--O, O--CO, where [0048]x is from 2 to 10; [0049]and
[0050]R18, R19, R20, R21, R22, R30,
R31[0051]are each H, alkyl, aryl, heteroaryl, alkenyl, alkynyl;
[0052]R3 is hydrogen or an alkyl, aryl, heteroaryl, alkynyl or
alkenyl radical, preferably hydrogen or an alkyl, heteroaryl or aryl
radical; [0053]which comprises reaction of a ligand precursor of the
general formula (III)

[0053] ##STR00005## [0054]where [0055]Q.sup.- is a monoanionic
counterion, preferably halide, pseudohalide, BF4.sup.-,
BPh4.sup.-, PF6.sup.-, AsF6.sup.- or SbF6.sup.-;
[0056]and [0057]G is H when Do2=C and [0058]is H or a free electron
pair when Do2=N, S, O or P; [0059]and [0060]the further symbols in
the ligand precursor of the formula III have the meanings given in
respect of the ligand of the formula II, [0061]wherein [0062]the reaction
comprises the use of a base and an auxiliary reagent selected from among
salts of Ag, Hg, Sb, Mg, B and Al, preferably salts of Ag, (route A) or
the use of a basic auxiliary reagent comprising at least one metal
selected from the group consisting of Ag, Hg, Sb, Mg, B and Al,
preferably Ag, (route B) and the ligand precursor of the general formula
III is [0063](A) reacted with the base, a metal complex comprising at
least one metal M1 and the auxiliary reagent (route A), [0064]or
[0065](B) reacted with the basic auxiliary reagent to give a protected
carbene and the protected carbene is subsequently reacted with a metal
complex comprising at least one metal M1 (route B);to give a
cyclometallated metal complex of the formula I.

[0066]Preference is given to ligands of the formula II and ligand
precursors of the formula III in which p and/or q are 0, i.e. no spacers
X and/or no donor atoms Do2 are present in the ligands of the
formula II and ligand precursors of the formula III.

[0067]The process of the invention makes it possible to prepare
cyclometallated transition metal-carbene complexes in good yields in a
simple reaction procedure.

[0068]For the purposes of the present invention, a bidentate ligand is a
ligand which is coordinated at two points to the transition metal atom
M1. For the purposes of the present patent application, the term
"two-dentate" is used synonymously with the term "bidentate".

[0069]For the purposes of the present invention, a monodentate ligand is a
ligand which coordinates at one point on the ligand to the transition
metal atom M1.

[0070]Depending on the coordination number of the metal M1 used and
the nature and number of the ligands L, K and carbene used, various
isomers of the corresponding metal complexes can be present for the same
metal M1 and the same nature and number of the ligands K, L and
carbene used. For example, in the case of complexes of a metal M1
having a coordination number of 6 (i.e. octahedral complexes), for
example Ir(III) complexes, both cis and trans isomers are possible when
the complexes have the general composition MA2B4 and fac and
mer isomers (facial/meridional isomers) are possible when the complexes
have the general composition MA3B3. In the case of square
planar complexes of a metal M1 having a coordination number 4, for
example Pt(II) complexes, cis and trans isomers are possible when the
complexes have the general composition MA2B2. The symbols A and
B are in each case one bonding point of a ligand, with not only
monodentate but also bidentate ligands being able to be present. In terms
of the abovementioned general composition, an unsymmetrical bidentate
ligand has one group A and one group B.

[0071]A person skilled in the art will know what cis/trans or fac/mer
isomers are. In the case of octahedral complexes, cis isomerism means
that in complexes of the composition MA2B4 the two groups A
occupy adjacent corners of an octahedron, while in the case of trans
isomerism the two groups A occupy opposite corners of an octahedron. In
complexes of the composition MA3B3, three groups of the same
type can occupy either the corners of one octahedral face (facial isomer)
or a meridian, i.e. two of the three ligand bonding points are in trans
positions relative to one another (meridional isomer). For details
regarding the definition of cis/trans isomers or fac/mer isomers in
octahedral metal complexes, see, for example, J. Huheey, E. Keiter, R.
Keiter, Anorganische Chemie: Prinzipien von Struktur und Reaktivitat, 2nd
revised edition, translated and expanded by Ralf Steudel, Berlin; N.Y.:
de Gruyter, 1995, pages 575, 576.

[0072]In the case of square planar complexes, cis isomerism means that in
complexes of the composition MA2B2 both the two groups A and
the two groups B occupy adjacent corners of a square, while in the case
of trans isomerism both the two groups A and the two groups B in each
case occupy the two diagonally opposite corners of a square. For details
regarding the definition of cis/trans isomers in square planar metal
complexes, see, for example, J. Huheey, E. Keiter, R, Keiter,
Anorganische Chemie: Prinzipien von Struktur und Reaktivitat, 2nd revised
edition, translated and expanded by Ralf Stendel, Berlin; N.Y.: de
Gruyter, 1995, pages 557 to 559.

[0073]In general, the various isomers of the metal complexes of the
formula I can be separated by methods known to those skilled in the art,
for example by chromatography, sublimation or crystallization.

[0074]The present invention thus relates both to the preparation of
individual isomers of the transition metal complexes of the formula I and
to the preparation of mixtures of various isomers in any mixing ratio.

[0075]The transition metal complexes of the general formula I prepared
according to the invention particularly preferably have a metal atom
M1 selected from the group consisting of Ir, Os, Rh and Pt, with
Os(II), Rh(III), Ir(I), Ir(III) and Pt(II) being preferred. Particular
preference is given to using Ir, preferably Ir(I) and Ir(III), very
particularly preferably Ir(III).

[0076]Suitable monoanionic or dianionic ligands L, preferably monoanionic
ligands L, which may be monodentate or bidentate, are the ligands
customarily used as monodentate or bidentate monoanionic or dianionic
ligands.

[0080]Suitable uncharged monodentate or bidentate ligands K are preferably
selected from the group consisting of phosphines, both monophosphines and
bisphosphines; phosphonates, both monophosphonates and bisphosphonates,
and derivatives thereof, arsenates, both monoarsenates and bisarsenates,
and derivatives thereof; phosphites, both monophosphites and
bisphosphites; CO; pyridines, both monopyridines and bispyridines;
nitriles, dinitriles, allyl, diimines, nonconjugated dienes and
conjugated dienes which form a π complex with M1. Particularly
preferred uncharged monodentate or bidentate ligands K are selected from
the group consisting of phosphines, both monophosphines and
bisphosphines, preferably trialkylphosphines, triarylphosphines or
alkylarylphosphines, particularly preferably PAr3, where Ar is a
substituted or unsubstituted aryl radical and the three aryl radicals in
PAr3 can be identical or different, particularly preferably
PPh3, PEt3, PnBu3, PEt2Ph, PMe2Ph, PnBu2Ph;
phosphonates and derivatives thereof, arsenates and derivatives thereof,
phosphites, CO; pyridines, both monopyridines and bispyridines, with the
pyridines being able to be substituted by alkyl or aryl groups; nitriles
and dienes which form a π E complex with M1, preferably
η4-diphenyl-1,3-butadiene, η4-1,3-pentadiene,
η4-1-phenyl-1,3-pentadiene,
η4-1,4-dibenzyl-1,3-butadiene, η4-2,4-hexadiene,
η4-3-methyl-1,3-pentadiene,
η4-1,4-ditolyl-1,3-butadiene,
η4-1,4-bis(trimethylsilyl)-1,3-butadiene and η2- or
η4-cyclooctadiene (each 1,3 and each 1,5), particularly
preferably 1,4-diphenyl-1,3-butadiene, 1-phenyl-1,3-pentadiene,
2,4-hexadiene, butadiene, η2-cyclooctene,
η4-1,3-cyclooctadiene and η4-1,5-cyclooctadiene. Very
particularly preferred uncharged monodentate ligands are selected from
the group consisting of PPh3, P(OPh)3, AsPh3, CO,
pyridine, nitriles and derivatives thereof. Suitable uncharged
monodentate or bidentate ligands are preferably
1,4-diphenyl-1,3-butadiene, 1-phenyl-1,3-pentadiene, 2,4-hexadiene,
η4-cyclooctadiene and η2-cyclooctadiene (each 1,3 and
each 1,5).

[0081]The number n of carbene ligands in uncharged transition metal
complexes in which the transition metal atom Ir(III) has a coordination
number of 6 is from 1 to 3, preferably 2 or 3, particularly preferably 3.
If n is >1, the carbene ligands can be identical or different.

[0082]The number n of carbene ligands in transition metal complexes in
which the transition metal atom Pt(II) has a coordination number of 4 is
1 or 2, preferably 2. If n is >1, the carbene ligands can be identical
or different.

[0083]The number m of monoanionic ligands L in the abovementioned case is
from 0 to 2, preferably 0 or 1, particularly preferably 0. If m is >1,
the ligands L can be identical or different but are preferably identical.

[0084]The number o of uncharged ligands K is dependent on whether the
coordination number 6 of Ir(III) or 4 of Pt(II) has already been reached
by means of the carbene ligands and the ligands L. If, when Ir(III) is
used, n is three and three monoanionic bidentate carbene ligands are
used, then o is 0 in the abovementioned case. If, when Pt(II) is used, n
is two and two monoanionic bidentate carbene ligands are used, then o is
likewise 0 in this case.

[0085]For the purposes of the present patent application, the following
applies to the groups Y1 and Y2:

the substituents of the groups Y1 and Y2 can together form a
bridge having a total of from two to four, preferably two or three, atoms
of which one or two atoms can be heteroatoms, preferably N, and the
remaining atoms are carbon atoms, so that Y1 and Y2 together
with this bridge form a five- to seven-membered, preferably five- or
six-membered, ring which may optionally have two or in the case of a six-
or seven-membered ring three double bonds and may optionally be
substituted by alkyl or aryl groups and/or groups having a donor or
acceptor action and may optionally comprise heteroatoms, preferably N,
with preference being given to a five-membered or six-membered aromatic
ring which is unsubstituted or substituted by alkyl or aryl groups and/or
groups having a donor or acceptor action, or the preferred five-membered
or six-membered aromatic ring is fused with further rings which may
optionally comprise at least one heteroatom, preferably N, preferably
six-membered aromatic rings.

[0086]The group Y1 can be joined to the radical R1 via a bridge
which can have the following meanings:

[0091]When Y1 and Y2 together form a bridge so as to form a
five- to seven-membered ring, the linking bridge to the radical R1
can be bound directly to the five- to seven-membered ring or be bound to
a substituent of this ring, with direct bonding to the five- to
seven-membered ring being preferred. The atom which is directly adjacent
to the N atom (in the general formula II) of the five- to seven-membered
ring is particularly preferably linked via a bridge to R1 if such a
linkage is present (cf., for example, the structures III, IIm, IIn, IIo
mentioned below). When the five- to seven-membered ring formed by means
of a bridge formed from Y1 and Y2 is fused with a further five-
to seven-membered ring, the linking bridge can be bound to an atom of the
fused-on ring (cf., for example, the structure IIk mentioned below).

[0092]Preferred bridged structures are mentioned by way of example below.
The bridges shown can also occur in other ligand systems used according
to the invention, e.g. in the ligand systems of the formulae IIa to j
mentioned below.

##STR00006##

[0093]The radicals R18, R20, R21R30 and R31 have
been defined above.

[0094]For the purposes of the present patent application, the terms aryl
radical or group, heteroaryl radical or group, alkyl radical or group and
alkenyl radical or group and alkynyl radical or group have the following
meanings:

An aryl radical (or group) is a radical which has a basic skeleton of from
6 to 30 carbon atoms, preferably from 6 to 18 carbon atoms, and is made
up of an aromatic ring or a plurality of fused aromatic rings. Suitable
basic skeletons are, for example, phenyl, naphthyl, anthracenyl or
phenanthrenyl. This basic skeleton can be unsubstituted (i.e. all carbon
atoms which are substitutable bear hydrogen atoms) or be substituted at
one, more than one or all substitutable positions of the basic skeleton.
Suitable substituents are, for example, alkyl radicals, preferably alkyl
radicals having from 1 to 8 carbon atoms, particularly preferably methyl,
ethyl or i-propyl, aryl radicals, preferably C6-aryl radicals which
may in turn be substituted or unsubstituted, heteroaryl radicals,
preferably heteroaryl radicals comprising at least one nitrogen atom,
particularly preferably pyridyl radicals, alkenyl radicals, preferably
alkenyl radicals having one double bond, particularly preferably alkenyl
radicals having one double bond and from 1 to 8 carbon atoms, or groups
having a donor or acceptor action. Suitable groups having a donor or
acceptor action are mentioned below. The aryl radicals very particularly
preferably bear substituents selected from the group consisting of
methyl, F, Cl, CN, aryloxy and alkoxy. The aryl radical or the aryl group
is preferably a C6-C18-aryl radical, particularly preferably a
C6-aryl radical, which may optionally be substituted by at least one
of the abovementioned substituents. The C6-C18-aryl radical,
preferably C6-aryl radical, particularly preferably has one or two
of the abovementioned substituents. In the case of a C6-aryl
radical, the one substituent is located in the ortho, meta or para
position relative to the further point of linkage of the aryl radical,
and in the case of two substituents, these can each be located in the
meta position or ortho position relative to the further point of linkage
of the aryl radical or one radical is located in the ortho position and
one radical is located in the meta position or one radical is located in
the ortho or meta position and the further radical is located in the para
position.

[0095]A heteroaryl radical or a heteroaryl group is a radical which
differs from the abovementioned aryl radicals in that at least one carbon
atom in the basic skeleton of the aryl radical has been replaced by a
heteroatom. Preferred heteroatoms are N, O and S. Very particular
preference is given to one or two carbon atoms of the basic skeleton of
the aryl radical being replaced by heteroatoms. In particular, the basic
skeleton is selected from among electron-rich systems such as pyridine
and five-membered heteroaromatics such as pyrrole, furan, pyrazole,
imidazole, thiophene. The basic skeleton can be substituted on one, more
than one or all substitutable positions of the basic skeleton. Suitable
substituents are the same ones which have been mentioned above in respect
of the aryl groups.

[0096]An alkyl radical or an alkyl group is a radical having from 1 to 20
carbon atoms, preferably from 1 to 10 carbon atoms, particularly
preferably from 1 to 8 carbon atoms. This alkyl radical can be branched
or unbranched and may optionally be interrupted by one or more
heteroatoms, preferably Si, N, O or S, particularly preferably N, O or S.
Furthermore, this alkyl radical can be substituted by one or more of the
substituents mentioned in respect of the aryl groups. It is likewise
possible for the alkyl radical to bear one or more aryl groups. In this
case, all of the abovementioned aryl groups are suitable. The alkyl
radicals are particularly preferably selected from the group consisting
of methyl and isopropyl.

[0097]An alkenyl radical or an alkenyl group is a radical which
corresponds to the abovementioned alkyl radicals having at least two
carbon atoms with the difference that at least one C--C single bond of
the alkyl radical has been replaced by a C--C double bond. The alkenyl
radical preferably has one or two double bonds.

[0098]An alkynyl radical or an alkynyl group is a radical which
corresponds to the abovementioned alkyl radicals having at least two
carbon atoms with the difference that at least one C--C single bond of
the alkyl radical has been replaced by a C--C triple bond. The alkynyl
radical preferably has one or two triple bonds.

[0099]For the purposes of the present application, the terms alkylene,
arylene, heteroarylene, alkynylene and alkenylene have the meanings given
for the alkyl, aryl, heteroaryl, alkynyl and alkenyl radicals with the
difference that the alkylene, arylene, heteroarylene, alkynylene and
alkenylene groups have two points of bonding to atoms of the ligand of
the formula II.

[0100]A bridge which is formed by Y1 and Y2 and has at least two
atoms of which at least one is a carbon atom and the further atoms are
preferably nitrogen or carbon atoms, with the bridge being able to be
saturated or preferably unsaturated and the at least two atoms of the
bridge being able to be substituted or unsubstituted, is preferably one
of the following groups: [0101]A bridge which has two carbon atoms or
one carbon atom and a nitrogen atom and in which the carbon atoms or a
carbon atom and a nitrogen atom are joined to one another by a double
bond so that the bridge has one of the following formulae, with the
bridge preferably having two carbon atoms:

##STR00007##

[0102]R23, R24, R11 and R11' are each, independently
of one another, hydrogen, alkyl, heteroaryl, alkenyl, alkynyl, aryl or a
substituent having a donor or acceptor action, [0103]or [0104]R23
and R24 together form a bridge having a total of from 3 to 5,
preferably 4, atoms of which one or two atoms may optionally be
heteroatoms, preferably N, and the remaining atoms are carbon atoms so
that this group forms a 5- to 7-membered, preferably six-membered, ring
which may optionally have, in addition to the existing double bond, one
or in the case of a six- or seven-membered ring two further double bonds
and may optionally be substituted by alkyl or aryl groups and/or groups
having a donor or acceptor action. A six-membered aromatic ring is
preferred. This can be unsubstituted or substituted by alkyl or aryl
groups and/or groups having a donor or acceptor action. It is also
possible for one or more further aromatic rings to be fused onto this,
preferably six-membered, aromatic ring. Any conceivable fusion is
possible here. These fused-on radicals can in turn be substituted,
preferably by the radicals mentioned in the general definition of the
aryl radicals. [0105]A bridge which has two carbon atoms and in which the
carbon atoms are joined to one another by a single bond so that the
bridge has the following formula:

##STR00008##

[0105]where R4[0106]R5, R6[0107]and R7 are each,
independently of one another, hydrogen, alkyl, heteroaryl, alkenyl,
alkynyl, aryl or a substituent having a donor or acceptor action,
preferably hydrogen, alkyl or aryl.

[0108]For the purposes of the present patent application, a group or a
substituent having a donor or acceptor action is one of the following
groups:

where the symbols have the following meanings: [0110]R4, R5,
R6, [0111]R7, R8, R9, R11[0112]and R11'
are each hydrogen, alkyl, aryl, heteroaryl, alkynyl or alkenyl or a
substituent having a donor or acceptor action, preferably hydrogen,
alkyl, heteroaryl or aryl; [0113]R10 is alkyl, aryl, heteroaryl,
alkynyl or alkenyl or 2 radicals R10 together form a fused-on ring
which may optionally comprise at least one heteroatom, preferably N, with
preference being given to 2 radicals R10 together forming a fused-on
aromatic C6 ring onto which, preferably six-membered aromatic ring
one or more further aromatic rings may optionally be fused, in which case
any conceivable fusion is possible and fused-on radicals may in turn be
substituted; or R10 is a radical having a donor or acceptor action;
[0114]with R4 or R5 in the group a, R8 in the group b, one
of the radicals R10 in the group c and R11 in the group d also
being able to be linked to R1 via a bridge which can have the
following meanings: [0115]alkylene, arylene, heteroarylene, alkynylene,
alkenylene, NR18, PR19, BR20, O, S, SO, SO2,
SiR30R31, CO, CO--O, O--CO and (CR21R22)x, where
one or more nonadjacent (CR21R22) groups can be replaced by
NR18, PR19, BR20, O, S, SO, SO2, SiR30R31,
CO, CO--O, O--CO, where [0116]x is from 2 to 10; [0117]and
[0118]R18, R19, R20, R21, R22, R30,
R31 are each H, alkyl, aryl, heteroaryl, alkenyl, alkynyl
[0119]where, with examples concerning preferred suitable bridges being
shown above (see formulae IIk to o); [0120]v is from 0 to 4, preferably
0, 1 or 2, very particularly preferably 0, where, when v is 0, the four
carbon atoms of the aryl radical in formula c which may optionally be
substituted by R10 bear hydrogen atoms; [0121]Y3 is hydrogen,
an alkyl, aryl, heteroaryl, alkynyl or alkenyl radical, preferably an
alkyl, heteroaryl or aryl radical, particularly preferably an alkyl
radical; [0122]or

##STR00013## [0124]where the symbols have the following meanings:
[0125]Z is CH or N, where from 0 to 3, preferably from 0 to 2,
particularly preferably 0 or 1, of the symbols Z can be N and if 1 symbol
Z is N, Z can be located in the o, m or p position, preferably in the o
or p position, relative to the point of linkage of the group to the group

[0125] ##STR00014## [0126]R12 is an alkyl, aryl, heteroaryl,
alkynyl, alkenyl radical, preferably an alkyl or aryl radical, or 2
radicals R12 together form a fused-on ring which may optionally
comprise at least one heteroatom, preferably N, with preference being
given to 2 radicals R12 together forming a fused-on aromatic C6
ring onto which, preferably six-membered aromatic ring one or more
further aromatic rings may optionally be fused, with any conceivable
fusion being possible and the fused-on radicals in turn being able to be
substituted; or R12 is a radical having a donor or acceptor action;
[0127]with the group of the structure

[0127] ##STR00015## [0128]also being able to be linked via the aromatic
basic skeleton or via one of the radicals R12 to Y1 via a
bridge which can have the following meanings: [0129]alkylene, arylene,
heteroarylene, alkynylene, alkenylene, NR18, PR19, BR20,
O, S, SO, SO2, SiR30R31, CO, CO--O, O--CO and
(CR21R22)x, where one or more nonadjacent
(CR21R22) groups may be replaced by NR18, PR19,
BR20, O, S, SO, SO2, SiR30R31, CO, CO--O, O--CO,
where [0130]x is from 2 to 10; [0131]and [0132]R18, R19,
R20, R21, R22, R30, R31[0133]are each H,
alkyl, aryl, heteroaryl, alkenyl, alkynyl; [0134]t is from 0 to 4,
where, when t is >1, the radicals R12 can be identical or
different, and t is preferably 0 or 1 and when t is 1 the radical
R12 is located in the ortho, meta or para position relative to the
point of linkage to the spacer X or when p is 0, to the point of linkage
to the nitrogen atom adjacent to the carbene carbon.

[0135]In the carbene ligands of the formula II, Y3 can be identical
to or different from the above-defined group and have the following
meanings which have already been mentioned above:

[0139]The definitions of the symbols correspond to the abovementioned
definitions.

[0140]The at least one carbene ligand of the formula II is very
particularly preferably selected from the group consisting of

##STR00022## ##STR00023##

where the symbols have the following meanings: [0141]Z, Z', Z'' are
identical or different and are each CH or N, where [0142]in the case of
Z: from 0 to 2 of the symbols Z can be N, preferably 0 or 1, and Z in the
case of 1 symbol Z being N can be located in the o or p position,
preferably in p position, relative to the point of linkage of the group
to the group

[0142] ##STR00024## [0143]in the case of Z': from 0 to 2 of the
symbols Z' can be N, preferably 0 or 1, and Z' in the case of 1 symbol Z'
being N can be located in the o or p position, preferably in p position,
relative to the point of linkage of the group to the group

[0143] ##STR00025## [0144]in the case of Z'': from 0 to 4 of the
symbols Z'' can be N, preferably from 0 to 3, particularly preferably
from 0 to 2, very particularly preferably 0 or 1; [0145]R12,
R12' are identical or different and are each an alkyl, aryl,
heteroaryl, alkynyl or alkenyl radical, preferably an alkyl or aryl
radical, or 2 radicals R12 or R12' together form a fused-on
ring which may optionally comprise at least one heteroatom, preferably N,
with preference being given to 2 radicals R12 or R12' together
forming a fused-on aromatic C6 ring onto which, preferably
six-membered aromatic ring one or more further aromatic rings may
optionally be fused, with any conceivable fusion being possible and the
fused-on radicals in turn being able to be substituted; or R12 or
R12' is a radical having a donor or acceptor action; [0146]t and t'
are identical or different and are each from 0 to 4, where, when t or t'
is >1, the radicals R12 or R12' can be identical or
different, and t or t' is preferably 0 or 1 and when t or t' is 1 the
radical R12 or R12' is located in the ortho, meta or para
position relative to the point of linkage to the nitrogen atom adjacent
to the carbene carbon; [0147]R4, R5, R6, [0148]R7,
R8, R9, R11[0149]and R11' are each hydrogen, alkyl,
aryl, heteroaryl, alkynyl or alkenyl or a radical having a donor or
acceptor action, preferably hydrogen, alkyl, heteroaryl or aryl;
[0150]R10 is alkyl, aryl, heteroaryl, alkynyl or alkenyl, preferably
alkyl, heteroaryl or aryl, or 2 radicals R10 together form a
fused-on ring which may optionally comprise at least one heteroatom,
preferably N, with preference being given to 2 radicals R10 together
forming a fused-on aromatic C6 ring onto which, preferably
six-membered aromatic ring one or more further aromatic rings may
optionally be fused, with any conceivable fusion being possible and the
fused-on radicals in turn being able to be substituted; or R10 is a
radical having a donor or acceptor action; [0151]with the group of the
structure

[0151] ##STR00026## [0152]also being able to be joined via the aromatic
basic skeleton or via one of the radicals R12 to R4 or R5
or the carbon atom to which R4 and R5 are bound in the groups a
and f, R8 or the carbon atom to which R8 is bound in the groups
b and g, one of the radicals R10 or one of the carbon atoms to which
R10 is bound in the groups c and h and R11 or the carbon atom
to which R11 is bound in the groups d and i via a bridge which can
have the following meanings: [0153]alkylene, arylene, heteroarylene,
alkynylene, alkenylene, NR18, PR19, BR20, O, S, SO,
SO2, SiR30R31, CO, CO--O, O--CO and
(CR21R22)x, where one or more nonadjacent
(CR21R22) groups may be replaced by NR18, PR19,
BR20, O, S, SO, SO2, SiR30R31, CO, CO--O, O--CO,
where [0154]x is from 2 to 10; [0155]and [0156]R18, R19,
R20, R21, R22, R30, R31[0157]are each H,
alkyl, aryl, heteroaryl, alkenyl, alkynyl [0158]where in the cases in
which the group of the structure

[0158] ##STR00027## [0159]is linked via a bridge to the carbon atom to
which R4 and R5 are bound (groups a and f), the carbon atom to
which R8 is bound (groups b and g), one of the carbon atoms to which
R10 is bound (groups c and h) or the carbon atom to which R11
is bound (groups d and i), and the respective radical R4 or R5,
R8, one of the radicals R10 and R11 is replaced by a bond
to the bridge; [0160]v is from 0 to 4, preferably 0, 1 or 2, very
particularly preferably 0, where, when v is 0, the four carbon atoms of
the aryl radical in formulae c and h which may optionally be substituted
by R10 bear hydrogen atoms; [0161]Y3 is hydrogen, an alkyl,
aryl, heteroaryl, alkynyl or alkenyl radical, preferably an alkyl,
heteroaryl or aryl radical, particularly preferably an alkyl radical.

[0162]The transition metal complexes of the formula I prepared by means of
the process of the invention can, if a metal atom M1 having a
coordination number of 6 is used, be present as the facial or meridional
isomer or an isomer mixture of facial and meridional isomers in any
ratios if they have a composition MA3B3, as described above.
For example, facial and meridional isomers of the transition metal
complex of the formula I are possible when n is 3 and m and o are each 0.
When the transition metal complexes of the formula I have a composition
MA2B4, the transition metal complexes can be pre-sent in the
form of cis/trans isomers in any ratios, as described above. Cis/trans
isomers of complexes of the formula I are possible, for example, when
M1 is a metal atom having a coordination number of 6 and n is 2 and
m is 2, with the two monodentate ligands L being identical, and o is 0 or
o is 2 and the two monodentate ligands K are identical and m is 0.

[0163]In the case of uncharged transition metal complexes in which the
transition metal atom Ir(III) has a coordination number of 6, the number
of preferred monoanionic bidentate carbene ligands n is at least 1 and
not more than 3. The number of preferred monoanionic bidentate carbene
ligands is preferably 2 or 3, particularly preferably 3. In the case of
n>1, the carbene ligands can be identical or different.

[0164]The transition metal complexes of the formula I can, if a metal atom
M1 which has a coordination number of 4 and forms square planar
complexes, be present as the cis or trans isomer or as an isomer mixture
of cis and trans isomers in any ratios if they have a composition
MA2B2, as described above. For example, cis/trans isomers of
the transition metal complexes of the formula I are possible when n is 2
and m and o are each 0.

[0165]In the case of uncharged transition metal complexes in which the
transition metal atom Pt(II) has a coordination number of 4, the number n
of preferred monoanionic bidentate carbene ligands n is 1 or 2,
preferably 1. In the case of n=2, the carbene ligands can be identical or
different.

[0166]The process of the invention is very particularly preferably used
for preparing a transition metal complex in which M1 is Ir(III)
having a coordination number of 6. In this Ir(III) complex, very
particular preference is given to n being 3, m being 0, o being 0, q
being 0, p being 0, Do1 being N and r being 1, with the remaining
symbols having the above-mentioned meanings.

[0167]According to the invention, the cyclometallated carbene complexes of
the formula I are obtained by reaction of a ligand precursor of the
general formula (III)

##STR00028## [0168]where [0169]Q.sup.- is a monoanionic counterion,
preferably halide, e.g. F.sup.-, Cl.sup.-, Br.sup.-, I.sup.-,
pseudohalide, BF4.sup.-, BPh4.sup.-, PF6.sup.-,
AsF6.sup.- or SbF6.sup.-, particularly preferably halide, e.g.
F.sup.-, Cl.sup.-, Br.sup.-, I.sup.-, or BF4.sup.-, very
particularly preferably I.sup.- or BF4.sup.-; very particularly
preferably I.sup.- or BF4.sup.-; [0170]and [0171]G is H when
Do2=C and [0172]is H or a free electron pair when Do2=N, S, O
or P; [0173]and [0174]the further symbols in the ligand precursor of
the formula III have the meanings given in respect of the ligand of the
formula II, [0175]wherein [0176]the reaction comprises the use of a base
and an auxiliary reagent selected from among salts of Ag, Hg, Sb, Mg, B
and Al (route A) or the use of a basic auxiliary reagent comprising at
least one metal selected from the group consisting of Ag, Hg, Sb, Mg, B
and Al (route B) and the ligand precursor of the general formula III is
[0177](A) reacted with the base, a metal complex comprising at least one
metal M1 and the auxiliary reagent (route A), [0178]or [0179](B)
reacted with the basic auxiliary reagent to give a protected carbene and
the protected carbene is subsequently reacted with a metal complex
comprising at least one metal M1 (route B).

[0181]In the process of the invention, the reaction of the ligand
precursor of the formula III is carried out in the presence of a base and
an auxiliary reagent (route A) or in the presence of a basic auxiliary
reagent (route B). It has been found that cyclometallated metal complexes
of the formula I can be obtained in good yields by means of the process
of the invention.

[0182]In a preferred embodiment of the process of the invention, the metal
complex comprising at least one metal M1, the ligand precursor of
the formula III, the base and the auxiliary reagent (route A) or the
metal complex comprising at least one metal M1, the ligand precursor
of the formula III and the basic auxiliary reagent (route B) are used in
particular ratios relative to one another.

[0183]In the case of route A of the process of the invention, the ratio of
metal complex comprising at least one metal M1, ligand precursor of
the formula III, base and auxiliary reagent is preferably
1:1-10:1-10:0.5-15 per metal atom M1 and number of carbene ligands
n, particularly preferably 1:1-5:1-5:1-7, very particularly preferably
1:1-2:1-2:1-1.5.

[0184]In the case of route B of the process of the invention, the ratio of
metal complex comprising at least one metal M1, ligand precursor of
the formula III and basic auxiliary reagent is preferably 1:1-10:0.5-5
per metal atom M1 and number of carbene ligands n, particularly
preferably 1:1-5:0.5-2.5, very particularly preferably 1:1-3:0.5-1.5.

[0185]In general, the process of the invention is carried out in a
solvent. Here, the term solvent encompasses both individual solvents and
solvent mixtures. Preference is given to using aprotic solvents. The
solvent is particularly preferably selected from at least one solvent
selected from the group consisting of dioxane, butanone, THF, toluene,
xylene, DMF, acetonitrile, DMSO, NMP and pyridine. Very particular
preference is given to using a solvent which comprises dioxane as sole
solvent or in admixture with one of the abovementioned solvents. It has
surprisingly been found that particularly good yields can be achieved
when the process of the invention is carried out in a solvent comprising
dioxane.

[0186]The process of the invention is generally carried out at
temperatures of from 60 to 200° C., preferably from 70 to
150° C.

[0188]In the preparation of iridium(III) complexes of the general formula
I (M1 in formula I is Ir), which are particularly preferred
according to the present patent application, it is possible to use, for
example, iridium(I) or iridium(III) complexes, in particular
[(μ-Cl)Ir(η4-1,5-cod)]2,
[(μ-Cl)Ir(η2-coe)2]2, Ir(acac)3,
IrCl3×n H2O, (tht)3, IrCl3,
Ir(η3-allyl)3, Ir(η3-methallyl)3, where cod
is cyclooctadiene, coe is cyclooctene, acac is acetylacetonate and tht is
tetrahydrothiophene. Particular preference is given to using Ir(I)
complexes, very particularly preferably
[(μ-Cl)Ir(η4-1,5-cod)]2 or
[(μ-Cl)Ir(η2-coe)2]2.

[0189]The auxiliary reagent used in the process of the invention according
to route A and the basic auxiliary reagent used according to route B
comprises a metal selected from the group consisting of Ag, Hg, Sb, Mg, B
and Al, preferably Ag.

Route A

[0190]The process of the invention comprises, according to route A, the
reaction of the ligand precursors of the general formula III with a base,
a metal complex comprising at least one metal M1 and an auxiliary
reagent selected from among salts of Ag, Hg, Sb, Mg, B and Al.

[0192]Suitable auxiliary reagents used according to route A are selected
from among salts of the abovementioned metals (Ag, Hg, Sb, Mg, B and Al,
preferably Ag). Suitable salts are inorganic salts such as
tetrafluoroborates, hexafluorophosphates, hexafluoroborates,
hexafluoroantimonates, hexafluoroarsenates, thiocyanates, cyanates,
nitrates, sulfates or perchlorates of the abovementioned metals or
organic salts such as trifluoroacetates or triflates of the
abovementioned metals. Here, the auxiliary reagents mentioned can be used
individually or in the form of mixtures of two or more auxiliary
reagents.

[0193]Preferred auxiliary reagents used in route A are Ag(I) salts.
Suitable Ag(I) salts are, for example, selected from among inorganic
salts such as AgBF4, AgPF6, AgSbF6, AgAsF6, AgSCN,
AgOCN, AgNO3, Ag2SO4, AgClO4 and organic salts such
as Ag(COOCF3), Ag(OTf). Very particular preference is given to
AgBF4 and AgPF6.

[0194]In route A of the process of the invention, preference is given to
using a base selected from among alkali metal silylamides, alkali metal
alkoxides, alkali metal hydrides, alkali metal acetates, alkali metal
hydroxides, alkali metal carbonates, Grignard compounds, alkylmetal
compounds and nitrogen-comprising bases as base. Here, the auxiliary
reagents mentioned can be used individually or in the form of mixtures of
two or more auxiliary reagents. Particular preference is given to using
one or more bases selected from the group consisting of KHMDS, NaHMDS,
LiHMDS, KOtBu, NaOtBu, LiOtBu, NaH, KOAc, NaOAc, LiOAc,
NEt3, BuLi, RMgHal, where R is alkyl, aryl, alkenyl, KOH, NaOH,
LiOH, Cs2CO3, K2CO3, Na2CO3,
Li2CO3, pyridine and DBU. Very particular preference is given
to using KHMDS, NaHMDS and/or LiHMDS as base.

[0195]The reaction time in the case of route A is generally from 1 to 100
hours, preferably from 1 to 48 hours.

[0196]The reaction according to route A can be carried out in one or more
stages.

[0197]The single-stage reaction is generally carried out by combining the
ligand precursor of the general formula III, the base, the metal complex
comprising at least one metal M1 and the auxiliary reagent in a
solvent and subsequently heating the mixture to the abovementioned
reaction temperature. After the reaction time indicated above, the
solvent is generally removed by methods known to those skilled in the
art, usually under reduced pressure, and the residue which remains is
worked up and/or purified by methods known to those skilled in the art.
The work-up and purification are usually effected by extraction, column
chromatography and/or recrystallization according to methods known to
those skilled in the art.

[0198]In the case of a multistage reaction, all orders of addition known
to those skilled in the art are possible. In a preferred embodiment, the
multistage reaction is carried out according to the following steps:
[0199](i) reaction of the ligand precursor of the formula III with the
base to give a reaction mixture, [0200](ii) reaction of the metal complex
comprising at least one metal M1 with the auxiliary reagent to give
a reaction mixture, [0201](iii) reaction of the reaction mixture obtained
in step (i) with the reaction mixture obtained in step (ii)to give a
cyclometallated metal complex of the formula I.

[0202]The reaction is preferably carried out in one of the abovementioned
solvents or solvent mixtures. Suitable ligand precursors of the general
formula III, bases, metal complexes comprising at least one metal M1
and auxiliary reagents have been mentioned above.

Step (iA)

[0203]The reaction in step (iA) is preferably carried out at room
temperature in one of the abovementioned solvents or solvent mixtures. In
general, the ligand precursor of the general formula III is admixed with
the base and the reaction mixture obtained is stirred at room
temperature.

Step (iiA)

[0204]The reaction in step (iiA) is generally likewise carried out at room
temperature. In general, the metal complex comprising at least one metal
M1 and the auxiliary reagent are mixed in one of the abovementioned
solvents or solvent mixtures and the mixture is stirred at room
temperature.

Step (iiiA)

[0205]In step (iiiA) the reaction mixture obtained in step (iA) is added
to the reaction mixture obtained in step (iiA). In principle, it is
likewise possible to add the reaction mixture obtained in step (iiA) to
the reaction mixture obtained in step (iA). In general, the addition is
carried out at room temperature and the mixture is subsequently heated to
the abovementioned reaction temperatures.

[0206]After the reaction time indicated above, the solvent is generally
removed by methods known to those skilled in the art, preferably under
reduced pressure. The reaction product is subsequently worked up and/or
purified as mentioned above in respect of the single-stage process.

[0207]The respective reaction product obtained after the steps (iA) or
(iiA) can be used directly without work-up or be worked up. In general,
no work-up is carried out and the respective reaction product obtained is
used directly in step (iiiA).

[0208]The desired cyclometallated carbene complexes of the formula I can
be obtained in good yields and in high purity by means of the process of
the invention according to route A comprising the use of a base and an
auxiliary reagent.

[0209]The present invention further provides for the use of an auxiliary
reagent selected from among salts comprising at least one metal selected
from the group consisting of Ag, Hg, Sb, Mg, B and Al together with a
base in a process for preparing cyclometallated carbene complexes.

[0210]Preferred auxiliary reagents and bases and also a preferred process
for preparing the cyclometallated carbene complexes have been mentioned
above.

Route B

[0211]According to route B, the process of the invention comprises
reaction of the ligand pre-cursors of the general formula III with the
basic auxiliary reagent comprising at least one metal selected from the
group consisting of Ag, Hg, Sb, Mg, B and Al to give a protected carbene
and subsequent reaction of the protected carbene with a metal complex
comprising at least one metal M1.

[0214]The reaction time according to route B is generally from 1 to 100
hours, preferably 6 to 56 hours.

[0215]The reaction according to route B of the process of the invention is
carried out as a multistage reaction according to the following steps:
[0216](iB) reaction of the ligand precursor of the general formula III
with the basic auxiliary reagent comprising at least one metal selected
from the group consisting of Ag, Hg, Sb, Mg, B and Al to give a
metal-carbene complex, [0217](iiB) subsequent reaction of the
metal-carbene complex with a metal complex comprising at least one metal
M1 to give a cyclometallated metal complex of the formula I.

[0218]The reaction is preferably carried out in one of the abovementioned
solvents or solvent mixtures. Suitable ligand precursors of the general
formula III, metal complexes comprising at least one metal M1 and
basic auxiliary reagents have been mentioned above.

Step (iB)

[0219]The reaction in step (iB) is preferably carried out at room
temperature in one of the abovementioned solvents or solvent mixtures. A
metal-carbene complex is obtained.

Step (iiB)

[0220]In step (iiB), the metal-carbene complex obtained in step (iB) is
reacted with the metal complex comprising at least one metal M1. In
a preferred embodiment, the metal complex comprising at least one metal
M1 is added to the metal-carbene complex obtained in step (iB). The
reaction mixture is stirred at the temperatures indicated above.

[0221]After the reaction time indicated above, the precipitate usually
formed is generally filtered off and washed with the solvent or solvent
mixture which is preferably used. The filtrate obtained is generally
evaporated to dryness by methods known to those skilled in the art,
usually by removal of the solvent under reduced pressure. The reaction
product obtained is generally worked up and/or purified further.

[0222]The work-up and purification are usually effected by extraction,
column chromatography and/or recrystallization according to methods known
to those skilled in the art.

[0223]The metal-carbene complex obtained in step (iB) can be used directly
without work-up or be worked up. In general, the metal-carbene complex
obtained is used without further work-up and/or purification in the
subsequent step (iiB).

[0224]The desired cyclometallated carbene complexes of the formula I can
be obtained in good yields and in high purity by means of the two-stage
process of the invention according to route B comprising the use of a
basic auxiliary reagent.

[0225]If the process of the invention according to route A or B is used
for preparing cyclometallated carbene complexes of the formula I which
can form cis/trans isomers or fac/mer isomers (facial/meridional
isomers), the process of the invention generally gives a mixture of the
cis and trans isomers or fac and mer isomers (facial/meridional isomers).
These isomer mixtures can be separated by methods known to those skilled
in the art, so that the pure cis or trans isomers or fac or mer isomers
are obtainable in each case.

[0226]The following examples illustrate the invention.

EXAMPLES

Method A for the Synthesis of the Complex

[0227]Potassium bis(trimethylsilyl)amide (0.5 M in toluene; 5 eq) is added
to a suspension of (benz)imidazolium salt (5 eq) in dioxane under argon
over a period of 30 minutes. The mixture is stirred at room temperature
for one hour before being added to a suspension of
1,5-cyclooctadieneiridium(I) chloride dimer (0.5 eq) and AgBF4 (1
eq) in dioxane under argon over a period of 30 minutes. The reaction
mixture is subsequently stirred at room temperature for one hour, at
70° C. for two hours and under reflux for 22 hours.

Method B for the Synthesis of the Complex

[0228]A suspension of (benz)imidazolium salt (5 eq) and silver(I) oxide
(2.5 eq) in dioxane is stirred at room temperature under argon for 16
hours. The mixture is admixed with 1,5-cyclooctadieneiridium(I) chloride
dimer (0.5 eq) and stirred under reflux for 16 hours. After cooling to
room temperature, the precipitate is filtered off and washed with
dioxane. The combined filtrates are evaporated to dryness and the crude
product is purified by column chromatography on basic aluminum oxide.

Example 1 Synthesis of Ir(cn-pmic)3

Synthesis of 1-(4-cyanophenyl)imidazole

[0229]1500 ml of dry dimethylformamide (DMF) are placed in a 1000 ml
four-necked flask while passing nitrogen over it and 72.67 g (0.6 mol) of
4-fluorocyanobenzene and 61.2 g (0.9 mol) of imidazole and finally 21.6 g
(0.9 mol) of sodium hydride are added. The reaction mixture is heated to
100° C., stirred at this temperature for 4 hours and subsequently
overnight at room temperature. The reaction mixture is then poured into
water and the resulting mixture is extracted a number of times with
dichloromethane. The organic phase is dried, evaporated on a rotary
evaporator and finally dried further at 60° C. under reduced
pressure. The yield is 94 g (93% of theory).

[0231]56 g (0.33 mol) of 1-(4-cyanophenyl)imidazole are dissolved in 560
ml water-free tetrahydrofuran in a 2000 ml one-necked flask with
condenser, admixed with 234.2 g (1.65 mol) of methyl iodide, stirred
briefly and allowed to stand for 48 hours without further stirring. The
solid contents of the flask are subsequently slurried with ethanol,
filtered off with suction and washed with ethanol until the washings are
virtually colorless. The residue is dried at 70° C. under reduced
pressure. The yield is 81.54 g (80% of theory).

[0234]The product is prepared by method A. The solvent is removed under
reduced pressure and the residue which remains is extracted with
methylene chloride. Purification of the extract by column chromatography
gives the product as a yellowish powder (58% of theory).

Synthesis Procedure 2:

[0235]The product is prepared by method B and eluted with dichloromethane.
The isomer mixture obtained is separated by column chromatography in
silica gel using ethyl acetate/cyclohexane 9:1 or by fractional
precipitation from acetonitrile. Yield: 75% mer i-somer and 4% fac
isomer.

Comparative Example 1

Synthesis Procedure 3 (Like Method B Without Ag Salt)

[0236]10 g (32 mmol) of the imidazolium iodide together with 150 ml of
dioxane are placed in a 500 ml three-necked flask and 64.3 ml of
potassium bis(trimethylsilyl)amide (0.5 M in toluene, 32 mmol) are added
at room temperature over a period of 30 minutes. The mixture is stirred
at room temperature for one hour before being added to a suspension of
2.16 g (3.2 mmol) of 1,5-cyclooctadieneiridium(I) chloride dimer in 200
ml of dioxane under argon over a period of 30 minutes. The reaction
mixture is stirred at room temperature for one hour, at 70° C. for
two hours and under reflux for 22 hours. The mixture is subsequently
evaporated to dryness and the residue is extracted with methylene
chloride. Purification of the extract by column chromatography gives the
product as a yellowish powder (24% of theory).

[0237]The yield of the desired product is significantly lower in
Comparative Example 1 than in Example 1 (synthesis procedures 1 and 2)
according to the process of the invention.

[0239]Sodium hydride (60% strength in mineral oil; 24.0 g, 0.60 mol) is
placed in a flask and admixed with N,N-dimethylformamide (80 ml). A
solution of benzimidazole (73.3 g, 0.60 mol) in N,N-dimethylformamide
(250 ml) is added dropwise to the suspension over a period of 1 hour.
After H2 evolution has ceased 4-chlorobenzonitrile (55.6 g, 0.40
mol) is added and the mixture is subsequently heated at 130° C.
for 10.5 hours. After cooling to room temperature, the reaction mixture
is poured into water (4 I) and the residue formed is filtered off with
suction, washed with water and dried under reduced pressure. This gives
90.6 g of 1-(4-cyanophenyl)benzimidazole which still comprises mineral
oil as contaminant.

[0241]1-(4-Cyanophenyl)benzimidazole (90 g, slightly contaminated with
mineral oil) together with THF (250 ml) is placed in a reaction vessel,
admixed with methyl iodide (116 g, 0.82 mol) and maintained at 40°
C. for 25.5 hours. The residue formed is filtered off, washed with
ethanol and dried under reduced pressure. This gives 123 g of
1-(4-cyanophenyl)-3-methylbenzimidazolium iodide.

Synthesis of
mer-tris[1-(4'-cyanophenyl)-3-methylbenzimidazol-2-ylidene-C2,C2]iridium(III)

##STR00030##

[0243]Synthesis Procedure 1:

[0244]The product is prepared by method A. The solvent is removed under
reduced pressure and the residue which remains is extracted with
methylene chloride. Purification of the extract by column chromatography
gives the product as a yellowish powder (60% of theory).

[0252]A 50 ml round-bottomed flask is charged with silver(I) oxide (0.076
g, 0.328 mol), 1-phenyl-3-methylimidazolium iodide (0.109 g, 0.381 mmol),
iridium trichloride hydrate (0.029 g, 0.097 mmol) and 20 ml of
2-ethoxyethanol. The reaction mixture is stirred and heated at
120° C. under nitrogen on an oil bath for 15 hours with the
reaction mixture being protected from light by means of aluminum foil.
The reaction mixture is cooled to room temperature and evaporated under
reduced pressure. To remove the silver(I) salts, the mixture is filtered
through Celite using dichloroethane as eluent. Removal of the solvent
under reduced pressure gives a white solid which is washed with methanol.
This gives 0.016 g (24% yield) of the meridional trisiridium complex in
the form of a white solid.

[0253]The yield of the desired product is significantly lower in
Comparative Example 3 than in Example 3 according to the process of the
invention.

[0256]1-(4-Chlorophenyl)imidazole (0.37 g, 2.07 mmol) is dissolved in THF
(5 ml) and subsequently admixed with methyl iodide (1.47 g, 10.4 mmol)
and allowed to stand for 20 hours. The precipitate formed is subsequently
filtered off and washed with ethanol and with petroleum ether and
subsequently dried under reduced pressure. This gives 0.46 g of
1-(4-chlorophenyl)-3-methylimidazolium iodide.

[0259]The product is prepared by method A. After cooling, the precipitate
is filtered off and the filtrate is subjected to purification by column
chromatography. This gives the product as a white powder (79% of theory).

[0261]4-Chloropyridine hydrochloride (91.6 g, 0.61 mol) is admixed with
saturated sodium hydrogencarbonate solution and extracted four times with
dichloromethane. The combined organic phases are dried over sodium
sulfate, filtered and evaporated to dryness. The oil obtained (52.7 g,
0.46 mol) is admixed with methylimidazole (38.1 g, 0.46 mol) and stirred
at 130° C. for 6 hours. After cooling to room temperature, the
mixture is dissolved in ethanol and the product is precipitated by
addition of n-hexane. Yield: 56.7 g (0.29 mol, 63%).

[0268]17.30 g (157 mmol) of 99% strength 2-aminophenol and 17.15 g (209
mmol) of anhydrous sodium acetate are added to a solution of 25.0 g (121
mmol) of 98% strength 2,6-dinitrochlorobenzene in 185 ml of anhydrous
ethanol under nitrogen while stirring. The reaction solution is refluxed
for 2 hours and subsequently cooled to room temperature. The red-violet
crystalline needles are separated off on a "black band" filter, washed
with water until the washings are colorless and dried at 50° C.
under reduced pressure. This gives 27.90 g (84% of theory) of shiny black
needles which melt at 189-192° C. (lit.: 191° C.).

[0271]27.70 g (101 mmol) of 2-[(2,6-dinitrophenyl)amino]phenol are
refluxed in 666 ml of 1% strength NaOH for 30 minutes while stirring.
After cooling to room temperature, the solid is filtered off with
suction, washed with hot water until neutral and dried at 80° C.
under reduced pressure. This gives 21.2 g (92% of theory) of black
crystals which melt at 168-171° C. (lit.: 166° C.).

[0274]21.20 g (92.9 mmol) of 1-nitrophenoxazine are suspended in 177 ml of
anhydrous ethanol and admixed with a solution of 83.84 g (372 mmol) of
tin(II) chloride×2H2O in 101 ml of concentrated HCl. The
reaction mixture is refluxed for 1 hour. After the reaction mixture has
been cooled to room temperature, the precipitate is filtered off with
suction, washed four times with a total of 430 ml of 10% strength HCl,
then with cold water and dried at 70° C. under reduced pressure.
This gives 18.45 g of gray needles.

[0277]18.45 g (78.6 mmol) of 1-ammoniophenoxazine chloride are suspended
in 85 ml of 85% strength formic acid. After addition of 5.38 g (78.6
mmol) of sodium formate, the reaction mixture is refluxed for 3.5 hours.
After cooling to room temperature, the reaction mixture is precipitated
in 700 g of 10% strength NaOH and stirred for another 30 minutes. The
solid is filtered off with suction on a "black band" filter, washed with
water and dried at 70° C. under reduced pressure. The crude
product (16.35 g) is stirred in 160 ml of methanol for 2 hours,
subsequently filtered off with suction, washed with methanol and dried at
70° C. This gives 13.09 g (80% of theory) of gray needles which
melt at 177-181° C. (lit.: 177-178° C.).

[0279]The preparation is carried out by a method based on that of H.
Shirai and T. Hayazaki, Yakugaku Zasshi 90 (1970) 588-593.

[0280]A solution of 5.48 g (26.3 mmol) of 2,10b-diaza-6-oxaaceanthrylene
and 18.42 g (130 mmol) of methyl iodide in 75 ml of methylene chloride
are refluxed for 26 hours. After the reaction mixture has been cooled to
room temperature, the solid is filtered off with suction, washed with
methylene chloride and dried at 75° C. under reduced pressure.
This gives 8.35 g (91% of theory) of analytically pure gray microcrystals
which melt at 284-291° C. (lit.: 295-297° C.).

[0282]7.55 g (50.0 mmol) of 98% strength trimethyloxonium
tetrafluoroborate are added to a solution of 10.41 g (50.0 mmol) of
2,10b-diaza-6-oxaaceanthrylene in 620 ml of water-free methylene chloride
which has been cooled to 0-3° C. in an ice bath. The reaction
mixture is allowed to warm to room temperature and stirred overnight.
Another 0.755 g (5.0 mmol) of 98% strength trimethyloxonium
tetrafluoroborate is added. After stirring at room temperature for 4
hours, the precipitate is filtered off with suction, washed with
methylene chloride and dried at 40° C. under reduced pressure
(crude yield: 11.35 g). The solid is recrystallized from 1000 ml of
methanol under nitrogen. This gives 8.90 g of analytically pure dark gray
microcrystals having a melting point of 230-238° C. The filtrate
is evaporated to dryness. The solid (3.39 g) is recrystallized from 132
ml of methanol. This gives another 1.42 g of dark gray microcrystals, so
that the total is 10.32 g (67% of theory).

[0285]The product is prepared by method A in o-xylene as solvent. After
cooling, the precipitate is filtered off and the filtrate is subjected to
purification by column chromatography. This gives the product as a
yellowish powder (21% of theory).

[0294]A suspension of 1-(2-bromo-4-cyanophenyl)-3-methylimidazolium iodide
(0.62 g, 1.6 mmol, 1 eq) and silver(I) oxide (0.19 g, 0.8 mmol, 0.5 eq)
in dioxane (80 ml) is stirred under argon at room temperature for 16
hours. The mixture is admixed with butanone (40 ml) and
1,5-cyclooctadieneplatinum(II) dichloride (0.60 g, 1.6 mmol, 1 eq) and
stirred under reflux for 16 hours. After cooling to room temperature, the
mixture is evaporated to dryness. The residue is taken up in
dimethylformamide (80 ml) and ad-mixed with 2,4-pentanedione (0.65 g, 6.4
mmol, 4 eq) and potassium tert-butoxide (0.73 g, 6.4 mmol, 4 eq). The
mixture is stirred at room temperature for 16 hours and at 100° C.
for 6 hours. After cooling to room temperature, it is evaporated to
dryness and the residue is washed with water.

[0298]The product is prepared by method A using
1,5-cyclooctadienerhodium(I) chloride dimer. The solvent is removed under
reduced pressure and the residue which remains is extracted with
methylene chloride. Purification of the extract by column chromatography
gives the product as a light-yellow powder (21% of theory).